U/Overflow problem with 2D histograms


I am investigating about a problem with overflow entries in 2D histograms. In some 2D histograms produced in my analysis with Athena, the total number of events doesn’t match the number of entries +U/Overflows.

I have understood that actually that the overflows were not an integer but the number of overflows/#bins(in the proper coordinate). On the other hand the overflows at the bin-coordinates (0,0), (0,NYbin+1) (NXbin+1,0), (NXbin+1,NYbin+1) where generally wrong.

I tried an example of my own by filling a 2D histogram and then checking the u/overflows and this worked fine. This means that is not a general problem.

All times I accessed the bins with “GetBinContent” method and the Root version is 04.02.00 (but I think that is still the same for the latest release).

Is this problem related to the way these histograms are filled (inside Athena ?) . Is there some other method to read the u/overflows in 2D histograms ? Does anyone have seen something similar ?

Many thanks for your attention.


It is likely that Athena fills ROOT histograms via the AIDA interface.
It is known that this interface is buggy, it has problems (among other things) with underflows/overflows, or profile histograms are wrong.
My only advice; Get rid of this interface asap if you do not want
to waist your time.